[1] Illinois 159 is a major north–south artery through the eastern portion of the metropolitan St. Louis, Missouri area.

Widening of a stretch of Illinois 159 to five lanes took place around 2006; the highway is now five lanes from Fairview Heights to Edwardsville, with the exception of downtown Collinsville, where a similar widening project was completed in 2012.

[citation needed] SBI Route 159 ran from Red Bud to Alton.

This created an unusual 3 way multiplex in downtown Edwardsville where you went north on 157, south on 159, and east on 143 for 2 blocks.

In 2003 Illinois 159 was rerouted through Edwardsville, which eliminated that multiplex.